Error Code P0955 is defined as Auto Shift Manual Mode Circuit. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to the present. Of course, specifications on the definition, troubleshooting, and repairs vary from one make and model to another.

For a vehicle with automatic transmission to shift like a manual, manufacturers place a switch connected to the gear lever, which sends an electrical signal to the transmission control module (TCM) each time the +/- direction of the shifter is pressed. This tells the sensor in the valve body which gear to engage. If there is a problem with one of the auto shift manual mode circuit components, the system registers the Error Code P0955.

Common Symptoms

  • Disabled manual shift function

Possible Causes

  • Damaged connectors or wirings
  • Defective Autostick transmission shift switch

How to Check

The first thing you need to check when diagnosing this code is to inspect the shifter mechanism and look for signs of moisture damage. This is one of the most common causes of failure, as spills around the gear lever are common.

Next, the auto stick shift switch must be tested as well to make sure it works. All the related wirings and connectors must also be checked for signs of damage and corrosion. Check for damaged of related components such as bent, broken, pushed-out, or corroded pins.

How to Fix

  • Repair or replacement of faulty wiring or damaged connectors
  • Replacement of auto stick transmission shift switch

Though this problem will not likely cause you to be stranded on the side of the road, it will keep you from using the manual shift function.